1. Field of the Invention
This invention relates to an electrical connector for interconnecting circuitry on a substrate and more particularly it relates to an electrical connector having an elastomeric body which can be positioned between two panel members such as printed circuit boards to interconnect corresponding aligned pads on the printed circuit boards
2. Description of the Prior Art
U.S. Pat. No. 3,985,413 discloses a miniature electrical connector which can be positioned between parallel spaced apart substrates, such as printed circuit boards to interconnect circuitry on each of the printed circuit boards. The connector consists of a generally cylindrical elastomeric body having a thin conventionally stable flexible film wrapped around the elastomeric body. Circuit traces are defined on the flexible film and face outwardly. When the elastomeric body is compressed between the two substrates or printed circuit boards, the elastomeric body supplies sufficient compressive force to establish an electrical connection with exposed pads on the printed circuit boards.
The electrical connector disclosed in U.S. Pat. No. 3,985,413 employs a film of polymeric material which is wrapped around the elastomeric body. The free ends of the film are joined together to maintain the film in surrounding relationship to the elastomeric body. The film is not attached directly to the elastomeric body, thus permitting relative movement therebetween when the body is placed under compressive loads.
U.S. Pat. No. 3,985,413 only discloses the elastomeric connector and does not describe the manner in which that elastomeric connector is mounted to interconnect separate circuit components, such as printed circuit boards. In use, that miniature electrical connector must be positioned within an insulating housing which is in turn attached to the electrical components. When used to interconnect printed circuit boards, that miniature elastomeric connector is positioned within a longitudinally extending recess in an insulating housing and the insulating housing is attached directly to the printed circuit boards. Although the circuit traces on the exterior of that miniature electrical connector have a width less than the spacing of conventional contact pads on printed circuit boards, in order to prevent easy alignment, it is still necessary to rely upon the housing to position the connector relative to the printed circuit board.
There are several drawbacks to the use of a separate connector of this type in conjunction with a separate housing. Foremost among these disadvantages is the additional manufacturing costs due primarily to the necessity of actual assembling the elastomeric connector in the housing. An additional problem which has been encountered with connectors of this type is that such connectors have not heretofore lent themselves to establishing an interconnection between the relatively widely spaced printed circuit boards. For example, such connectors have not proven suitable for interconnection of circuitry on boards spaced apart on the order of 0.500 inches or more. When a circular connector of the type disclosed in U.S. Pat. No. 3,985,413 is used for such widely spaced boards. The diameter of the circular elastomeric member occupies an excessive amount of space. Connectors of the type shown in that patent but having an oval cross section have been employed to save space. However, a limit is reached in which the major axis of the oval cross section exceeds the minor access dimension by such a degree that proper alignment and stability of the connector becomes difficult to maintain.
One example of an electrical connector which was in part intended for interconnecting relatively widely spaced boards is disclosed in U.S. Pat. No. 4,057,311. That connector also employs a thin film having circuit traces disposed on its exterior and uses elastomeric members to establish contact pressure when the compressive force is applied thereto. The miniature electrical connector disclosed in that patent also employs a central rigid body having a trough-like recess in which the elastomeric members are positioned. The thin film circuitry is, however, positioned along the rigid body and is to be held in position by a plurality of elastomeric members spaced side by side in the common recess. It can be appreciated that the assembly costs encountered with elastomeric connectors of more conventional construction would be magnified for the electrical connector shown in U.S. Pat. No. 4,057,311, at least in part because of the large number of separate parts which must be employed.